I took my truck over to my buddy's shop. He's pretty convinced that my 2nd cylinder from the front of the truck on the passenger side (#3?) is causing my truck to be violently loud, vs not loud at all.

So I know that the truck does not sound like any other 7.3 (that's running right), it has a distinctive clack. It's not a knock, it's not a tick, it's a clack. Everyone recognizes my truck from its distinctive clack, it's that pronounced. So we tested which cylinder it was on, the noise is 100% coming from cylinder #3. It's not the injector, because when the injector is swapped out, it's not making noise on that new cylinder.

It's definitely in the rotating assembly. He thinks it's a bent connector rod (but I have a 2001. It should have PMRs, meaning it should shatter rather than bend??). The other mechanic thinks it could be a wrist pin. What are some things you think could be causing it. I'm taking it to shop tomorrow, I can get readings tomorrow from a scan-tool. As far as we've tested, no loss of compression, no loss of power, no white smoke, no miss-fires, nothing. Just a STUPID amount of noise - which I've personally come to live with, but now that I'm trying to build power, I don't want a weak link just waiting to snap on me.

If you guys want, I can post a video of my 7.3 clacking away so you can hear the noise, just understand it won't be studio quality sound.

If you haven't lost any power, or the engine isn't missing I would doubt that you bent a connecting rod. I guess it could be a wrist pin bushing, but I have never seen one fail, or be out of spec unless there is a pile of miles on the engine. I have mic'd pin bushings on engines with 300,000 on them and they were within spec. As for having PMRs, you have to go by serial number of the engine rather than the year of the truck. It is a more accurate way of telling what you have. Also, I have seen engines that were serialed as having forged rods that had PMRs, and vice versa. The best way to tell is to pull the inspection plug in the block and look in the crankcase. If you see a nut holding the rod cap on then it's forged, if you see the head of a bolt then its PMRs. If I were a betting man, I would bet that you spun a rod bearing, but that is just a guess. If you have, DO NOT reuse that rod, it will never hold a bearing correctly again, no matter how you have it machined.

After hearing that, if I had to guess I would say a callopsed lifter. I may have spelt that wrong. WHEN THE TRUCK IS NOT RUNNING, and the problem cylinder (I think you said #3) is at TDC how much play do you have between the rocker arm and the push rod?

After hearing that, if I had to guess I would say a callopsed lifter. I may have spelt that wrong. WHEN THE TRUCK IS NOT RUNNING, and the problem cylinder (I think you said #3) is at TDC how much play do you have between the rocker arm and the push rod?

How do I check if the cylinder is at TDC? I may have to just take this back over to the mechanic, I don't trust myself to doing much more than disconnecting an injector. With my luck, I'll drop a single metal shaving in a cylinder and grenade the whole thing.

I think you may be on to something with the collapsed lifter, because we had brought that up before. Either way... I'll let you guys know. If you can think of anything else to test, let me know, she's going in tomorrow for her new front-end suspension parts and her new bed.

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